Telephone-system.



- PATENTED MAY 8, 1906-."

' I 0. L. 'BOYGB.

TELEPHONE SYSTBM. APPLIOATION FILED MAR. 7 190 2.

P 4 gm 7 a M J ATTORNEK IHE NORRIS PETERS co., wnsnlrlm'cm n. c

50 be and is UNITEii STATES PATENT OFFICE;

CHARLES L. BOYCE, OF DETROIT, MICHIGAN, ASSIGNOR TO AMERICAN TELEPHONE TELEGRAPH COMPANY, ,A CORPORATION NEW j YORK.

Specification of Letters Patent.

TELEPHONE, SYSTEM.

Application filed March'T. 1902. Serial'No. 97,025.

T at whom it may co rtcern:

Be it known that 1, CHARLES L. Boron, a

citizen of the United States, residing at Detroit, county'of Wayne, State of Michi an, have invented a certain new and useful mprovement in Telephone Systems; and I declare the following to be a fullfclear, and exact descri tion of the invention, such as will enable 0t er's skilled in the art to which'it ro ertains to make and use the same, reference e111 had to the accompanying drawings, a

whic form a part of this specification.

This invention relates to'that class of telephoneexchange systems which employ a I 5 central. source of cii'irent for the'substationtransmitters and for the central-station call and switch board signals, and more specifically relates to an improved plan and an imroved arrangement of circuits and apparatus for the operation and control of such signals.

Its objects are-to carryout the varioussuboperations of receiving call-signals, the Withdrawal of said signals in due season; and the appropriate display and withdrawal of su-' 2 5 pervisory and disconnecting signals in animproved and highly-efficient manner; to dispense with relays 1n the main circuit-conductors of the switch-cord; to control the supervisor'y signals without the employment of 0 shunt circuits, and to provide that the relays concerned in o crating the call and su' ervisory signals oteach substation-circuit s all belong to such line-circuit, and shall therefore be independent of the switch-cord cir- 3 5 cuits, thus aiding in the avoidance of faults.

and facilitating their location and removal when they occur. For the attainment of these objects this invention, while dispensing with switch-cord relays, does not involve the employment of any greater number of permanently-associated relays than have heretofore been used. 4 The helices of the line or call relay are divided into substantially equal portions which are connected in the two sides of the main circuit, respectively, and since Patented May a, 1906.

suit, but in a local circuit associatedthere with and adapted to .be completed .when the a switch-plug is inserted in a switch-socket of said line through registering local-circuit contacts of the said socket and: plug. The super'visory signal associated with the switch plug is also in the local circuit which 0 mins the said'second relay,-and in addition thereto there is a resistance ada ted under different conditions to be includes in said local circuit or short-circuited therefrom, and thereby to vary the strength of the current flowing therein and to determine the display ornoiidis lay of thesupervisory sign'alj he invention therefore consists iin' com-' bining the call-signal and its local circuit with a line-relay ermanently in the line-'cir cult and an auXi iary relay in a local circuit completed through. switch-plu and socket contacts in such manner tliatt e said signal local circuit shall be closed and its signal displa ed when the said line-relayis excited an the, said auxiliary-relay uneXcited an that the said signal-circuit having thus been closed and the said signal displayed shall be 0 sued for the withdrawal of said; signal w enever the said auxiliary relay shall likewise be excited and become operative.

It also consists in combining the supervisory signal, its local circuityand a resistance governing the strength of current 1n such O11- cuit, and consequently the. display 'or nondisplay of said signal with the line-rela ,in such manner that the said resistance sha 1 be short-circuited'and withdrawn from the supervisory-signalcircuit when the line-relay is unexcited, but shall be introduced into said circuit 0n .and during the operation of said line-relay, so that the display of said supervisory signal can-only occur when its circuitshall have been completed through the.

switch-socket of a substation-circuit whose line-relay has not previously been excited by the closingat the substation of the main cirthroughits switch-cord with any substation-1 circuit which has thus been closed it is ada ted to serve as a disconnecting-signal,there or;

cuit including said line-relay. Obviously when the said-supervisory signal is associated Since on replacing the receiver at suchJs'ta- .tion on its switch-hook the said main circuit 'isflopened, the excitation of the line-relay short-circuited.

7 switch and the circuit leads throu h the bell;

- is taken from the hook, the main circuit is mary of said coil being in the main circuit,

thereof ceases and the resistance controlling the current of the supervisory-signal circuit is i It consists also in combining the supervisory signal and its local c rcuit with the line-relay, the winding of the auxiliary relay, and a shunt or short circuit round a portion. of said-winding constituting a considerable portion of the resistance thereof in such manner that the said shunt shall be open when the said relay is excited and closed when the said relay is unexcited, thereby rendering the relation of such high-resistance portion of said winding to the supervisory-signal circuit and the display of said signal de endent upon the condition of the said line-re ay.

The drawing which accompanies this specification is a diagram showing the electrical connections of -two substation-circuits and switching devices at the central station provided with call and supervisory signals comprehending my invention.

Referring to said drawin L L are substation-circuits converging rom substations A A to a central station X. At said substations the usual apparatus is provided and comprises the receiver 't, the transmitter b,

the call-bell a; the condenser c, and the suspension switch 8, these devices being arranged and associated in a well-knownrnanner. When the line is unemployed, the receiver it hangs on the hook of the suspensionbut sincethe condenser is included he circuit is open for steady currents while the rapidlyalternating currents which operate the bell readily'pass. When, however, the receiver closed conductively through the transmitter and the steady cu rent from the central-station battery is enabled to circulate throughthe circuit. To reduce the resistance of the circuit, the receiver at is connected therewith by means of an induction-coil in a manner frequently adopted, the low-resistance pritogether with. the transmitter. The re ceiver at substation A is resting on the hook, showing that circuit L is disengaged; but the receiver at substation A' has been taken from the hook, so that the switch 8 has assumed its upper position, has closed the maincircuit through the transmitter, and has manifested a call (as presently will be explained) at the central station. v

The apparatus now to be considered is wholly at the central station. Each substation-circuit has certain individually-appropriatcd appliances comprising a permanently-connected line-relay, a call-signal, an auxiliary relay, a resistance device which may and preferably does "consist of a portion of the Winding of said auxiliary relay, and as many switch-sockets as may be necessary acremaining portion of the central station 'ated .wit switch-cords, sufficient of course in number for the efficient transaction of business. For each switch-cord provided with the usual answering and companion plugs there is also a listening-key, a callingkey, and a supervisory signal. The central source of current Qmaybe common to a large number of main circuits and switch-cords, and the call-generator Y and operators telephone U are common also to a large number of switchcords, being-under the control of the ringing and listening" keys thereof.

- H is the permanently-connected line-rela Y with its magnetizing-coilin two half-win ings e f, connected, respectively, in the two sides 1 and 2 of the main -circuit'L'by means ofeXtension-conductors 3 and 4, which after passing through the said relay-coils continue switch apparatus is comprisedin or associto the poles of the batteryQ. 'The half windings e and f are connected to reinforce one another for the excitation of the relay when the circuitis .closedby takin up the telephone from the substation-switcfii.

with winding M, which has a much higher" resistancesay four hundred and eighty W is the auxiliary relay, which also hasits ohmsand, in fact, constitutes in itself a resistance device forming, as will presently be explained, an important feature of thls an:

vention. It is not necessary that ,the "re-- sis'tance-windingM shall actually be a part of the exciting-coil-of relay W. It might, ifdesired, be formed of German-silver wire wound over the exterior of winding N of relay 'W or might be formed into a special resistancecoi independent altogether of the relay, but connected serially therewith andconnected in the circuit thereof in the same place that it now occupies. The constructlon shown, wherein it does form apart of the relay-magnet coils, is, however, preferable, and is a aconvenientiway of increasing the efficiency of said relay under certain conditions.

. I and'J are the front and back limit-stops for the armature g of line-relay H and are both electrical contactoint's.

K and a: are the bac and forward limitstops of the armature k of the auxiliary relay .W, the back or resting stop alone beingan electrical contact-point.

0 is the line or call-signal device, shown as a small glow-lamp,- the same being connected in a local circuit passing through the said resting-contact K of the auxiliary relay. andthe forward or workin contact I of' the line.- relay, the said pointsk and I being united by a conductor 13. The said signal-Ocan therefore be displayed only whenthe 'line or call-si nal relay becomes excited and operatesw e the auxiliary relayremains passive. Again, should the saidline-relay have acted to display the signal O,'the said signal can obviously be Withdrawn by the. subsequent excitement and operation of the auxiliary relay N.

The switch-sockets J have long and short contact-s rings B and C, representing and lay H, and the said armature g has an electr cal connection 15 with the main conductor 4, and thereby with the pole'v of the battery. The ilocal circuit of the line-signal may be traced from said pole 'v by conductors 4 and 2 5 15, 'armature'g, contacts I, conductor 13, contact K of armature 7c of relay W, conductor 8, including lamp 0 to main conductor 3 and pole y of said battery. t

' The high-resistance winding M, connected at one end with its associate winding N and branch conductor 6, is connected at its other end with conductor 7, which joins main conductor4, leading from pole v of the battery.

Substation-circuit L as will be seen, has

3 5 similar and similarly connected and arranged apparatus, the same parts bein marked by 1i e"- reference letters-or numera s, to which, however, index characters are added. It is, however, to be observed that since line L is supposed to be initiating a communication, the receiver 15 having at its substation been taken from the hook-switch its line-relay H is excited and the armature g attracted for ward to close the local circuit of'the lampsignal Circuit L however,being as yet disengaged, its relay H has not become excited, and the armature g thereof remains- I un'attracted and in connection with its rest ing-contact J. y 1

Z is a cord-circuit, as many such as are necessary being of course employed.

P is the answering-plug with its conductingtilp E, ring F, and sleeve G, adapted when the p ug is thrust into socket J to register and con 5 5 nect electrically'with the socket members C,

B, and D, respectively, and P is the com anionrplug similarly constructed and provi ed; is the ringing-key; T the listening key,

both of usual construction and arrangements S and V are condensers, and R and R supervisory signals. The cord conductor 10 unites the tips of the two plu s through the ,condenser S, and the cord con uctor "l1 similarly unites the [ring-contacts F F thereof sockets of the said two circuits.

' mature 9 will of course open the local circuit through condenser- V, and these constitute 6 5 the main switch-cord conductors through and by means of which the main conductors of substation-circuit L are united to those of L when the plugs are respectively laced in ach plug has its own local or supervisory-signal circuit conductor, and these 9 and 9*, respectively, lead through their associated signals R and R to thepole 1 of battery Q, the location'- cuits of said signals being completed when the plugs controlling them are placed in their sockets. The local circuit thus completed may, however, be continued to the other pole of: the'battery through either orie of two different paths, and the display of the signal depends'upon which of these two paths canbe taken by the current, this again depending upon thelposition of the armature g of the linerelay. he said local circuit of plug P, for example,'the plug being inserted, continues from the hameiece D. by conductor 5,

through winding of relay W, then through the high-resistance winding M, and by conductors 7 and 4 to the-battery atjpole 'v, When the su ervisory-signal circuit is, como pleted throug this path, the current flowing therein is in virtue of the included high resistance M too small for the operation of the signal-R, which accordingly is not displayed;

but'itthe line-relay H had not been previously excited and if'its armature had not been attracted, but had remained in connection with its resting contact J the said highresistance winding would have been shortcircuited through conductor 6, contact J armature g, and conductors 15 and 4, the cur'- rent then beingstrong enough to operate sig nal R, which would accordingly be displayed. In the apparatus of line L the relay H l .t not attracted its armature g ioiward, and the local circuit is therefore shown as being closed through the-back contact J* and the short-circuiting connection 6 Thus when r the plug P is thrust into socket 'J the supervisor-y signalR will be displayed, and such display' will continue until substation A responds to a call by taking the receiver from the hook. Such action resulting in the excitement of relay H and the attractionfo'i ar- I I 5 at J and withdraw the signal.

The operation oi this system is simple. Substation A desiring to talk with substation A has removed his receiver tirom the hook,

which has moved to its upper contact and 'closed'the line-circuit. The current flowing from battery Q through the reinforcing wind I ings' of relay H- excites said relay, which has attracted its armature g, closing the circuit of call-signal O for the display thereof and opening the short circuit throughconductdr 6 round the high resistance M, which is thus brought into the supervisory signal circuit of line L. Responding o the display of signal O'the central operator inserts the answeringplug P into socket J and ressing the listening as choking-coils to prevent the passage that way of the voice-currents. The signal R does not operate, because the'high resistance M being in its circuit the current is too weak. Ascertaining the line Wanted, the

plug P is inserted in the-switch-socketJ the!" of, and the signal R is at once displayed,

the high resistance M of its circuit being shunted by conductor 6 and the back or restin contact J of the armature g of relay- H he display of thissignal indicates. that the receiver at substation A thus far has not been removed from itshook. The operator now presses the ringing-key T and sendsa call-current over circuit L The subscriber -at A lifts the receiver from the switch, thereby closing the line-circuit L, and answers. This action excites relay H which attracts its armature 9 causing it to break the su ervisory circuit at Jand to withdraw signa Theattraction of armature 9 does not, however, bring about the exhibition of line-signal I O becaus the circuit thereof has already been opene "at k. The two substations are thus brought into communication; and the replacement of the receiver on the suspension- 'switch at either station operates to transmit a disconnect-signalthat is, when A replaces his receiver the si nal R is displayed, ecause the main circuit is broken, and the relay H, l'osingits excitement, allows the armature g-to'be-retracted and=to close-the short circuit round the high resistance M, and when A replaces his receiver the signal R is in like manner displayed, so that the plugs may be pulled out, which permits all of the mechanism to resume its nor.

mal condition. With the exception of-"t he windings of relay W, for which suitable magnitudes have been stated, the magnitudes of the several relays and signals and of the bat tery may all be such as are customarily employed. It will be seen that when my"improvement is adopted the talking-circuit through the cord-conductors 10 and 11 is freed from the impedance of supervisory relays, which heretofore have been connected "therein. In practice, for purposes not directly involved in the operation of this invenhas connected the main conduc-.

tion, a ground connection R extending from the pole v of the I claim-,-- l

l. The combination in a telephone centralstation switchboard apparatus, of a line-relay in a. main telephone-circuit a supervisory signal associated with a switch-cord; a local supervisory circuit contai ing said si nal; an auxiliary relay with a win ing of'hig resistance also included in said local su ervisory circuit to reduce the strength 0 current therein and prevent the operation of said signal; and a' shunt or short circuit round a ortion of said high-resistance winding lea ing .throu h contacts of-said line-relay, and controlle by said line-rela to cut out said por tion, and permit the isplay of said supervisory signal when saidrelay 'is unexcited, and to leavesaid portion in said circuitand prevent the'display of said signal, when the same is excited; substantially as described.

change system, of a main substation-circuit controlled by aswitch at the substation; a switch-socket 'for said main circuit and a switch-plug adapted to be inserted therein, the said socket and plug having i egistering main and local circuit contacts; a local supervisory circuit at said central station adapted to be completed through the local contacts of said socket and plug; a local call-circuit at the central station; a supervisory-signal device in the local call-circuit and two re ays; one a line relay having its winding in the main substation-circuit at the central station and the other. an auxiliary relay having itswinding in the supervisory circuit, said relays cooperat-- ing to control the supervisory circuit and the ,LperViSory and call signals t erein.

3. The combination in a telephone-excontrolled by a switch at the substation; a-

switch-plug adapted to be inserted therein, the said socket and plug having registerlng, main and local circuit contacts; a local superto be completed throughthe,local contacts of said socket and plug; a local call-circu t at the central station; a supervisory-signal device 1n the local call-circuit and two relay's, one a line-relay having its winding in the main subother an auxiliary relay having its winding in the supervisory circuit, said re a'ys having associated armature-contacts in the local call and supervisory circuits respectively whereoration of the supervisory andcall signas therein.

2. The combination in a .telephone-exby said circuits are controlled to efi'edt the 0 general battery, is employed. 6 5

in thesupervisory circuit; a call-s1 nal device local call-circuit and the o eration of the suchange system, of a main substation-circuit switch-socket for said main circuit and a visory circuit at said central station adapted I 1 i I the supervisory circuit; a call-signal device in -station-circuit at the central station and the 4i, The combination in a telephone-exchange system, of a main substation-circuit controlled by a switch at the substation; a sw tch-socket for said main circuit and a sw1tch-' lug adapted to be inserted therein,

' the sai' socket and plug-having-registering to be completed through the local contacts'of main and local circuit contacts; a local supervisor-y circuit at said central station adapted said socket and plug; a local call-circuit at the central station a supervisory-signal device in the supervisory circuit a call-signal device in p the local call-circuit; andtwo relays, one a line-relay having its Winding in the main substation-circuit at the central station; its forward contacts in the local call-circuit and its loca lca land supervisory circuits and the o 5; eration of. the call 1 and supervisory signa s backcontacts in the local supervisory circuit, and the'other anauxiliary relay having its windm 1n the local su ervis'ory circuit and its bac contact in t e localtcall-circuit,

whereb said relays cooperate to control the therein. 7

5. The combination in a telephone-exchange system,'of a main'substation-circuit controlled by a switch at the substatiom a one s line-relay having its windin in the main substation-circuit at the centra station,

switch-socket for said main circuit and a switchlug ada ted to be inserted therein,

the sai socket and plug having registering main-and local circuit contacts; a localsupervisory circuit at said central station adapted to be completed through the local contacts of said socket and plug; a local call-circuit at the central station; a supervisory-Si nal dcvicein the supervisory circuit; a ca l-signal device in the local call-circuit; and two relays,

its forward contacts in the local'call-circuit and its back ci intacts in the local supervisory circuit, and the other an aum'liary relay hav ing its winding in the local supervisory circult; and a shunt or short circuit of the su ere visory circuit round a portion of the win in of theauxiliaryrelay and through-the bac r cdntacts of the line-relay, to cut outsaid portion and permit the operation of the supervlsttr'y signal when said line-relay is unexcited and to leave said portion in said circuit and paevent: the operation of said sigr'lal when the saane is excite 6. in a telephone-exchange system, the

ccmbinationnuth a tele'phonedine extending from afs'ubstation' to an exchange, of a linerelayat'the exchange, a source of current adapted to be closed through said line-relay through the agency of substation apparatus, cord connecting apparatus for connecting said line with another forconversation, acutofi rela included in a high-resistance circuit control ed b the cord connectin apparatus, a line signa jointly controlled y said line and tout-off relays, a supervisory signal included in said high-resistance ?circuit; .means whereby the deenergization of said "line-relay causes a decrease in the resistance of the circuit through said supervisorysignal-v 7 In a telephone-exchange system, the I combination with a telephone-lineextending from a substation to an exchange, of a lineadapted to be closed through saidline-relay cord connecting apparatus for connecting said line with another for conversation, a cutoff relay included in a high-resistance circuit controlled by the cord connecting apparatus,

armatures of said relays, the circuit through said line-signal being closed when the linerelay is energized andthe cut-,ofi relay is deener izedfa supervisorysignal included in said high-resistance circuit, and means wherecauses a decrease the resistance of the circult through said supervisory signals. 8. In a telephone-exchange sy from a substation to an exchange, of a linerelay at the exchange, a source of current adapted to beclosed through said line-relay through the agency of substation apparatus,

said line with another for conversation, a cutoff relay included in a circuit controlled by in said circuit, a line-si nal jointly controlled by said line and cut-o5 relays, a supervisory signal included. in the circuit controlled by the cord connecting apparatus, and means whereby the deenergizatio'n of said line-relay ,and the cut-cit relay is denergized, a supervisory signal included in the circuit controlled by the cord connecting apparatus, and means whereby the deenergization of said line-relay-causes the closure of a low-resistance shunt-circuit about 'said resistance. 10. in a telephone-exchange system, the

relay at the exchange, a source of current through the agency of substation apparatus,

a line signal in a local circuit including the by the denergization of said line-relaycord' connecting apparatus for. connecting 1 ing closed when the line-relay is energized the comb'nation with a telephone-line extending the cordconnecting: apparatus, a resistance closes a low-resistance shunt-circuit about combination, with a telephone line extending p from a substation to ani exchange, of a l1l16- relaylat'fthe exchange, a source of current adapted to be closed through said line-relay through the agency of substation apparatus, cord connecting apparatus for connecting said line with another for conversation, a cutofi relay included in a circuit controlled-by the cord connecting apparatus, a line-signal included in a-local circuit containing the armatures of said relays, the circuit with said line-signal being closed When the line-relay is IO energized and the cut-off relay is giz ed, and a supervisory signal included in the I denersubstantially" as described.

In testimony whereof I sign this specifica-- tion in the presence of two witnesses.

' CHARLES L. BOYCE.

"Witnesses MAY. E. Korr, CHARLns F. BURTON. 

